The invention relates to liquid crystal devices and methods of making liquid crystal devices. Liquid crystal technology has many applications. For example, liquid crystal devices can be used to selectably vary the retardance, intensity, and/or polarization of an incident beam. Such devices may include a single liquid crystal component or multiple liquid crystal components in optical series. Each liquid crystal component includes two substrates sandwiching a layer of liquid crystals, and the substrates each support an electrode. An electric field can be applied across the liquid crystal layer via the electrodes to cause a change in the orientation of the liquid crystals, which in turn causes an incident beam to see a change in the retardance of the liquid crystal layer. The component(s) can be combined with additional optical elements (e.g., polarizers, waveplates, fixed retarders, etc.) for modifying the output of an incident beam. As is common in the art, such liquid crystal devices can be configured in both reflective and transmissive arrangements.
One problem that can occur when using liquid crystal devices is that undesired reflections from one or more interfaces in the device can interfere with the main output beam and degrade the optical performance of the device. Such interference effects can be especially significant for a coherent input beam. Sometimes a wedge is introduced into the device to reduce the overlap between the main output beam and one or more of the reflected beams.
A second problem that can occur is thermal expansion of the liquid crystals within the device. Such expansion can degrade the optical performance of the device and ultimately lead to mechanical failure (e.g., failure of the perimeter seal).
Another consideration relates to the manufacturability of such liquid crystal devices. For many applications (e.g., telecom applications), the liquid crystal device should be small and compact. Unfortunately, it can be difficult to achieve robust and economical manufacture when handling and assembling such small components.